Sony is moving ahead in R&D for bio batteries powered by sugar1, a substance synthesized by plants from sunlight in photosynthesis. Sugar is an energy source in abundant supply on earth, and bio batteries powered by this renewable resource are promising, environmentally conscious energy devices.
These bio batteries work by utilizing enzymes to break down carbohydrates (sugar). In this way, the batteries harness power generation principles in living organisms. Instead of being used for regular life processes, the energy is used as electrical energy.
Sugar is a naturally occurring and renewable energy source produced by plants through photosynthesis from CO2 and water,which makes this bio battery expected as an environmentally conscious battery for the future.
The Sony prototype battery produces 50 mW, the world's highest output2 among passive3 bio batteries. This is enough power to play music on a flash-based Walkman.
Although studies are still at the level of basic research, Sony is looking into practical applications of eco-batteries that tap into plant-derived sugar as an energy source.
1. Bio battery
An electricity generation device that utilizes energy sources such as carbohydrates, protein, amino acids, fat by digesting enzymes. Since 2001, Sony's research has been supported by Professor Kenji Kano's laboratory (formerly professor Tokuji Ikeda's laboratory) at the Division of Applied Life Sciences, Graduated School of Agriculture, Kyoto University, Kyoto, Japan, which specializes in bioelectrochemistry. The results presented here are based on Sony's original technological developments, inspired by the lab's advanced research activities.
2. 50 mW: World's highest power output as of August 23, 2007, based on Sony research.
3. Passive-type battery
A system in which reactive substances such as sugar and oxygen are absorbed into electrodes through a process of natural diffusion. In contrast, systems in which reactive substances are supplied by force (stirring, convection) are referred to as "active-type". In general, passive-type systems have a more simple structure suitable for miniaturization, whereas active type systems have a more complicated structure and are suited to higher power devices.
Sugar-powered Walkman
What enables these bio batteries to be sufficient to power a Walkman are two technical achievements that offer the world's highest power output in this kind of battery. The first is a system for efficiently breaking down sugar to generate electrical energy. High concentrations of enzymes and mediators that support electronic conduction are immobilized by the electrodes (specifically, by the cathode) while retaining their vital energy. Additionally, a new electrode structure was developed. Breaking down sugar requires oxygen, and the anode structure ensures a plentiful supply, thanks to an ideal moisture level inside the electrode itself. The optimal electrolyte these technologies provide yields exceptionally high output.
Sony is now studying new directions in practical applications of these promising achievements.
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